This problem (or something like it) seems to crop up fairly often.
Untill this:
http://dvinfo.net/conf/showthread.php?t=122958
I had seen no solution.
Before you do anything rash with this info, a couple of provisos:
1. We have not heard how this saga played out. Apart from the two tapes apparently saved, there is no indication that it was 100% successful.
2. I strongly recommend you do NOT attempt this yourself, unless you are fully competent in tape deck maintenance. Better to park the camera and tapes in front of a competent technician and let them do it.
3. Ensure that all other possible reasons for your tape problems have been eliminated - dirty heads, damaged tapes etc etc. I can see no way this procedure can fix such problems, in fact it could turn a bad scenario into a disaster.
4. Not having independent verification of the success or otherwise of this procedure, I do not and cannot take any responsibility for it's success or failure in any circumstance.
With the above said, if you are experiencing the classic symptoms of this problem:
HDV, BSOD (Blue Screen Of Death) on play, image on FF/ REW,
then this would appear to be the only solution (that I know of).
CS
PS: No, I still haven't figured out WHY it happens or WHY this works.